Trophic interactions between the Kelp Gull (Larus dominicanus) and Royal and Cayenne terns (Thalasseus maximus maximus and Thalasseus sandvicensis eurygnathus, respectively) in a human-modified environment

2019 ◽  
Vol 97 (10) ◽  
pp. 904-913
Author(s):  
Cristian Marinao ◽  
Nicolás Suárez ◽  
Pablo Yorio
Keyword(s):  
Trophic Interactions ◽  
Interspecific Interactions ◽  
Isotope Analysis ◽  
Trophic Niche ◽  
Trophic Relationships ◽  
Isotopic Niche ◽  
Main Prey ◽  
Kelp Gull ◽  
Recreational Fishery ◽  
Larus Dominicanus

Many closely related seabirds nest in mixed colonies, and this association may result in interspecific interactions such as competition for common resources and kleptoparasitism. Trophic interactions were evaluated between the Kelp Gull (Larus dominicanus Lichtenstein, 1823) and Royal and Cayenne terns (Thalasseus maximus maximus (Boddaert, 1783) and Thalasseus sandvicensis eurygnathus (Saunders, 1876), respectively) nesting at a mixed-species colony in an area with high availability of recreational fishery waste for the opportunistic Kelp Gull. Diet analyses were based on gull chick stomach content samples and direct observations of food delivered to tern chicks in 2013 and 2014, complemented in 2014 with carbon and nitrogen stable isotope analysis of chick whole-blood samples. Main prey species of Kelp Gull chicks were Cynoscion guatucupa (Cuvier, 1830), a demersal species obtained from recreational fishery waste, Argentine anchovies (Engraulis anchoita Hubbs and Marini, 1935), and insects. Engraulis anchoita and Odontesthes spp. were the main prey of both tern species. Trophic niche and isotopic niche overlap between the Kelp Gull and Royal and Cayenne terns was low. Kelp Gull kleptoparasitism on Royal and Cayenne terns was ≤2.5% and <0.6%, respectively. The use of anthropogenic food subsidies by Kelp Gulls may be mediating the trophic relationships among species, favouring their use of predictable and abundant fishery waste over a more unpredictable pelagic schooling fish such as E. anchoita.

Trophic ecology of large pelagic fish in the Saint Peter and Saint Paul Archipelago, Brazil

2019 ◽  
Vol 70 (10) ◽  
pp. 1402 ◽  
Author(s):  
F. V. Albuquerque ◽  
A. F. Navia ◽  
T. Vaske ◽  
O. Crespo ◽  
F. H. V. Hazin
Keyword(s):  
Trophic Ecology ◽  
Feeding Habits ◽  
Saint Paul ◽  
Pelagic Fish ◽  
Trophic Niche ◽  
Trophic Relationships ◽  
Main Prey ◽  
Important Prey ◽  
Saint Peter ◽  
Prey Items

Trophic relationships of large pelagic predators can determine the structure and dynamics of oceanic food webs. The feeding habits and trophic ecology of five large pelagic fish (Acanthocybium solandri, Coryphaena hippurus, Elagatis bipinnulata, Thunnus albacares and Thunnus atlanticus) in the Saint Peter and Saint Paul Archipelago were evaluated to determine whether there is a trophic-niche overlap or resource partitioning among them. Eighty prey items found in 1528 stomachs were identified and grouped into Cephalopoda, Cnidaria, Crustacea, Gastropoda, Teleostei and Tunicata. Exocoetidae and Scombridae were the main prey in the diet of Acanthocybium solandri. In C. hippurus, Cheilopogon cyanopterus and Exocoetus volitans were the most important prey items, whereas C. cyanopterus was the main prey for T. albacares. Thunnus atlanticus consumed a great proportion of invertebrate species, with shrimps of Sergestidae family being particularly important. The gastropod Cavolinia sp. was the most important prey for E. bipinnulata. The five species had a high trophic specialisation and a high trophic level (&gt;4.4), whereas most dietary overlaps were consistently low. The most important factor for diet dissimilarity was the consumption of Exocoetidade. All species were classified as top predators with varied diets, indicating their structural and functional importance in the food web of the Archipelago.

scholarly journals How fishing intensity affects the spatial and trophic ecology of two gull species breeding in sympatry

2018 ◽  
Vol 75 (6) ◽  
pp. 1949-1964 ◽  
Author(s):  
Diana M Matos ◽  
Jaime A Ramos ◽  
Joana G Calado ◽  
Filipe R Ceia ◽  
Jessica Hey ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Habitat Preferences ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Temporal Segregation ◽  
Fishery Discards ◽  
Individual Tracking ◽  
South Portugal

Abstract Fisheries produce large quantities of discards, an important resource for scavenging seabirds. However, a policy reform banning discards, which is soon to be implemented within the EU, will impose a food shortage upon scavengers, and it is still largely unknown how scavengers will behave. We studied the diet (hard remains), trophic (stable isotope analysis), and foraging (individual tracking) ecology of two gull species breeding in sympatry: Audouin’s gull Larus audouinii (AG) and yellow-legged gull Larus michahellis (YLG), in South Portugal, under normal fishery activity (NFA; work days) and low fishery activity (LFA; weekends), over two consecutive years. We established a pattern of dietary, spatial, and temporal segregation between the two gull species. Under LFA, yellow-legged gulls reduced their time spent at-sea, thus foraging more in alternative habitats (e.g. refuse dumps) and widening their isotopic niche (i.e. generalist behaviour). Contrastingly, Audouin’s gull had a narrower trophic niche (i.e. specialist behaviour), foraging exclusively at-sea, reducing the amount of demersal fish and increasing the amount of pelagic fish in their diet. Under NFA, both species foraged mostly at-sea, feeding almost exclusively on fish, with increased consumption of demersal species (i.e. fishery discards). In general, yellow-legged gull had a broader trophic niche (i.e. generalist behaviour) when compared with the narrower isotopic niche of Audouin’s gull (i.e. specialist behaviour). Overall, both gull species relied heavily on fishery discards. However, there was visible dietary, spatial, and temporal segregation between the two species, associated with their dietary and habitat preferences that could be attributed to the availability of anthropogenic resources, such as fishery discards.

scholarly journals Individual niche trajectories in nesting green turtles on Rocas Atoll, Brazil: an isotopic tool to assess diet shifts over time

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Karoline Fernanda Ferreira Agostinho ◽  
Leandro Rabello Monteiro ◽  
Ana Paula Madeira Di Beneditto
Keyword(s):  
Trophic Ecology ◽  
Isotope Analysis ◽  
Trophic Niche ◽  
Northeastern Brazil ◽  
Diet Shift ◽  
Isotopic Niche ◽  
Temporal Window ◽  
Temporal Dimension ◽  
Green Turtles ◽  
Diet Shifts

Abstract In this study, multi-tissue (yolk and carapace) stable isotope analysis was used to assess individual isotopic niche trajectories of nesting green turtles on Rocas Atoll, off northeastern Brazil, and to reveal a diet shift in the temporal dimension. The diet trajectories of individual green turtles were highly directional, with a stronger component towards decreasing values of δ15N from carapace to yolk. When the green turtles are in their foraging sites (temporal window measured by the yolk samples), they are more herbivores. Conversely, in a broader temporal window, the green turtles demonstrate a carnivore-omnivore strategy, such as represented by heavier δ15N values in the carapace. This finding confirms a temporal diet shift. This is the first study that applies trophic niche trajectories for sea turtles, adding a new isotopic tool to understand the trophic ecology of these migrant animals.

Evidence for inter- and intraspecific trophic niche separation among deepwater elasmobranchs on the southern Great Barrier Reef, Australia

2020 ◽  
Vol 636 ◽  
pp. 107-121
Author(s):  
SEM Munroe ◽  
CL Rigby ◽  
NE Hussey
Keyword(s):  
Great Barrier Reef ◽  
Trophic Ecology ◽  
Isotope Analysis ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Feeding Strategies ◽  
Niche Separation ◽  
Isotopic Niche ◽  
Barrier Reef ◽  
Trawl Fishery

Quantifying the trophic structure and interactions of deepwater (>200 m depth) elasmobranch assemblages is required to improve our understanding of deepwater ecosystems and the impacts of increased deepwater exploitation. To this end, we investigated the trophic ecology of deepwater elasmobranchs on the Great Barrier Reef (GBR) using a stable isotope (δ13C and δ15N) approach. Our study included 4 species captured in the southern GBR deepwater eastern king prawn trawl fishery: the eastern spotted gummy shark Mustelus walkeri, the piked spurdog Squalus megalops, the pale spotted catshark Asymbolus pallidus, and the Argus skate Dentiraja polyommata. The δ13C and δ15N values of all 4 species ranged from -18.6 to -16.2‰ and 8.3 to 13.8‰, respectively. The small δ13C range was likely due to the limited number of unique carbon baseline sources typically found in deepwater environments. Despite this, 3 of the 4 species exhibited relatively low core (40% SEAb) isotopic niche overlap (<1 to 44%). Isotopic niche separation may be driven by multiple interacting factors including morphology, feeding strategies, or resource partitioning to reduce competition. Isotope analysis also provided evidence for intraspecific variation; S. megalops, D. polyommata and M. walkeri exhibited significant increases in δ15N (~3‰) and δ13C (~2‰) with size. Latitude, longitude, and depth had statistically significant but comparatively minor effects on isotope values (≤1‰) of the 4 species. Cumulatively, our results indicate that isotopic variation among deepwater elasmobranchs on the GBR is principally driven by size and species-level differences in resource use.

scholarly journals Trophic ecology of the seagrass-inhabiting footballer demoiselle Chrysiptera annulata (Peters, 1855); comparison with three other reef-associated damselfishes

2020 ◽  
Vol 146 (1) ◽  
Author(s):  
Gilles Lepoint ◽  
Loïc N. Michel ◽  
Eric Parmentier ◽  
Bruno Frédérich
Keyword(s):  
Stable Isotope ◽  
Trophic Ecology ◽  
Close Association ◽  
Isotope Analysis ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Seagrass Meadows ◽  
Turf Algae ◽  
Herbivorous Species

Many damselfishes (Pomacentridae) are herbivorous or omnivorous with an important contribution from different kinds of algae in their diet. They display different levels of territoriality and farming behavior, from almost non territorial to monoculture farmers. In addition, a few species inhabit seagrass meadows but, presently, none can be considered as seagrass-eating specialists. The footballer demoiselle, Chrysiptera annulata, is found in the seagrass meadows on the reef flat of the Great Reef of Toliara (Madagascar, Mozambique Channel). In the light of this unusual habitat for a pomacentrid, this study aimed to answer three questions: 1) What is the diet of C. annulata? 2) Do the resources supporting this diet include seagrass? 3) Does its trophic niche overlap those of other sympatric damselfishes (Pomacentrus trilineatus, Chrysiptera unimaculata and Plectroglyphidodon lacrymatus) living in close association with macrophytes or eating algae? Stomach content examination and stable isotope analysis showed that the footballer demoiselle is not a seagrass consumer but is an omnivorous/herbivorous species heavily relying on algal resources and small invertebrates. SIAR, a stable isotope mixing model, indicated it assimilated large amounts of turf algae, and various benthic or planktonic invertebrates in lower proportions. SIBER metrics revealed that the isotopic niche of the footballer demoiselle partly overlaps that of its congener, C. unimaculata, but not those of P. trilineatus and P. lacrymatus. Trophic strategies of C. annulata differed both from farming species such as P. lacrymatus and from less territorial herbivores such as P. trilineatus. Its seagrass meadow habitat on the Great Reef of Toliara allows the conquest of an unusual habitat for damselfishes and could limit competition with C. unimaculata, a species displaying the same territorial behavior and the same isotopic niche but living on the reef itself.

Diet and isotopic niche of eastern sand darter (Ammocrypta pellucida) near the northern edge of its range: a test of niche specificity

2019 ◽  
Vol 97 (9) ◽  
pp. 763-772 ◽  
Author(s):  
Jacob Burbank ◽  
Mary Finch ◽  
D. Andrew R. Drake ◽  
Michael Power
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Stomach Content ◽  
Isotope Analysis ◽  
Resource Limitation ◽  
Niche Overlap ◽  
Stomach Content Analysis ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Population Declines

Niche specificity can predispose species to population declines during periods of resource limitation, yet trophic niche specificity is poorly known for many small-bodied freshwater fishes. Applying a two-tiered approach involving stomach content and stable isotope analyses, we examined the diet and trophic niche of the threatened eastern sand darter (Ammocrypta pellucida (Putnam, 1863)) and co-occurring fishes in the Thames River, Ontario, Canada. As with previous studies, stomach content analysis revealed that eastern sand darter consumed a variety of benthic organisms including Chironomidae, Cladocera, Ostracoda, Oligochaeta, and Ephemeroptera; however, proportional contributions of prey groups differed based on stable isotope analysis, highlighting the potential for seasonal variation in prey consumption. Despite evidence of a generalist strategy, stable isotope analysis indicated eastern sand darter exhibited a relatively narrow trophic niche relative to co-occurring fishes. Trophic niche overlap was relatively minor between eastern sand darter and drift-feeding fishes (spotfin shiner (Cyprinella spiloptera (Cope, 1867)), emerald shiner (Notropis atherinoides Rafinesque, 1818), and buffalo sp. (genus Ictiobus Rafinesque, 1820)), but was more evident between eastern sand darter and benthic and benthopelagic fishes (johnny darter (Etheostoma nigrum Rafinesque, 1820) and blackside darter (Percina maculata (Girard, 1859))), indicating that competition with these species may be more likely during periods of prey scarcity.

scholarly journals The food web in a subterranean ecosystem is driven by intraguild predation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrea Parimuchová ◽  
Lenka Petráková Dušátková ◽  
Ľubomír Kováč ◽  
Táňa Macháčková ◽  
Ondřej Slabý ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Interactions ◽  
Intraguild Predation ◽  
Linear Models ◽  
Niche Overlap ◽  
Trophic Niche ◽  
High Availability ◽  
Large Prey ◽  
Arthropod Predators ◽  
Body Sizes

AbstractTrophic interactions of cave arthropods have been understudied. We used molecular methods (NGS) to decipher the food web in the subterranean ecosystem of the Ardovská Cave (Western Carpathians, Slovakia). We collected five arthropod predators of the species Parasitus loricatus (gamasid mites), Eukoenenia spelaea (palpigrades), Quedius mesomelinus (beetles), and Porrhomma profundum and Centromerus cavernarum (both spiders) and prey belonging to several orders. Various arthropod orders were exploited as prey, and trophic interactions differed among the predators. Linear models were used to compare absolute and relative prey body sizes among the predators. Quedius exploited relatively small prey, while Eukoenenia and Parasitus fed on relatively large prey. Exploitation of eggs or cadavers is discussed. In contrast to previous studies, Eukoenenia was found to be carnivorous. A high proportion of intraguild predation was found in all predators. Intraspecific consumption (most likely cannibalism) was detected only in mites and beetles. Using Pianka’s index, the highest trophic niche overlaps were found between Porrhomma and Parasitus and between Centromerus and Eukoenenia, while the lowest niche overlap was found between Parasitus and Quedius. Contrary to what we expected, the high availability of Diptera and Isopoda as a potential prey in the studied system was not corroborated. Our work demonstrates that intraguild diet plays an important role in predators occupying subterranean ecosystems.

scholarly journals Inter-Specific and Intra-Specific Competition of Two Sympatrically Breeding Seabirds, Chinstrap and Gentoo Penguins, at Two Neighboring Colonies

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 482
Author(s):  
Won Young Lee ◽  
Seongseop Park ◽  
Kil Won Kim ◽  
Jeong-Hoon Kim ◽  
Jong-Ku Gal ◽  
...  
Keyword(s):  
Isotope Analysis ◽  
Niche Partitioning ◽  
Limited Resources ◽  
Isotopic Niche ◽  
Seabird Species ◽  
Δ13c And Δ15n ◽  
Foraging Area ◽  
Colonial Seabird ◽  
Gps Tracks ◽  
Colony Level

Theory predicts that sympatric predators compete for food under conditions of limited resources. Competition would occur even within the same species, between neighboring populations, because of overlapping foraging habits. Thus, neighboring populations of the same species are hypothesized to face strong competition. To test the hypothesis that intra-specific competition is more intense than inter-specific competition owing to a lack of niche partitioning, we estimated the foraging area and diving depths of two colonial seabird species at two neighboring colonies. Using GPS and time-depth recorders, we tracked foraging space use of sympatric breeding Chinstrap and Gentoo penguins at Ardley Island (AI) and Narębski Point (NP) at King George Island, Antarctica. GPS tracks showed that there was a larger overlap in the foraging areas between the two species than within each species. In dive parameters, Gentoo penguins performed deeper and longer dives than Chinstrap penguins at the same colonies. At the colony level, Gentoo penguins from NP undertook deeper and longer dives than those at AI, whereas Chinstrap penguins did not show such intra-specific differences in dives. Stable isotope analysis of δ13C and δ15N isotopes in blood demonstrated both inter- and intra-specific differences. Both species of penguin at AI exhibited higher δ13C and δ15N values than those at NP, and in both locations, Gentoo penguins had higher δ13C and lower δ15N values than Chinstrap penguins. Isotopic niches showed that there were lower inter-specific overlaps than intra-specific overlaps. This suggests that, despite the low intra-specific spatial overlap, diets of conspecifics from different colonies remained more similar, resulting in the higher isotopic niche overlaps. Collectively, our results support the hypothesis that intra-specific competition is higher than inter-specific competition, leading to spatial segregation of the neighboring populations of the same species.

scholarly journals Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis

2006 ◽  
Vol 86 (6) ◽  
pp. 1443-1447 ◽  
Author(s):  
D. Fourgon ◽  
G. Lepoint ◽  
I. Eeckhaut
Keyword(s):  
Stable Isotopes ◽  
Potential Benefit ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Tracer Experiment ◽  
Trophic Relationships ◽  
Nitrogen Stable Isotopes ◽  
Carbon And Nitrogen ◽  
C And N ◽  
The One

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiuroids, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiuroids. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate δ13C values between both adult species. The high proportion of 13C in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston from their associated host, O. scolopendrina.

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